Heat exchange system



Patented Nov. 16, 1937 2,099,310

UNITED STATES PATENT OFFICE HEAT EXCHANGE SYSTEM Frederick D. Mensing,Philadelphia, Pa. Application February 3, 1934, Serial No. 709,560

10 Claims. (Cl. 237-63) The invention relates to heat exchange sysratus,or the secondary heat exchange apparatus tems, and involves a method andapparatus for and its connecting piping. circulating the liquid heattransfer medium in Another object of the invention is the provisuchsystems. y 1 sion, in a heat exchange system, of a method and In theoperation of heat exchange systems apparatus whereby a minimum drop inthe temvarious methods have been employed heretofore perature of aliquid heat transfer medium may to effect the circulation of a liquidheat transfer be maintained between the primary heat exmedium throughthe entire system of heat exchange apparatus and the secondary heatexchange apparatus such as heating or cooling dechange apparatus. vices,flow pipes, heat emitting or absorbing de- A further object of theinvention is the provivices and return pipes, and to liquid withdrawingsion, in a heat exchange system utilizing a liquid devices. With themethods heretofore known, heat transfer medium, of a method andapparathe mechanical circulating systems which have tus whereby thesecondary heat exchange appabeen used have been so operated as tonecessitate ratus, such as heat emitting appliances or heata forcedcirculation throughout the entire heat absorbing appliances, may be fedfrom a source exchange system, through the primary heat exofsubstantially uniform temperature. change apparatus, or through thesecondary heat It is another object of the invention to proexchangeapparatus. In any such system a relavide, in a heat exchange systemutilizing a liquid tively large amount of liquid must be circulated,heat transfer medium, a method and apparatus and, asa consequence, arelatively large amount whereby the lag in heating or cooling the sec-2O of power is required to maintain the forced circuondary heat exchangeapparatus furthest from lation. y the primary heat exchange apparatusmay be In the various systems heretofore known, both avoided. gravityand mechanical means have been utilized Another object of the inventionis the provision for effecting the circulation of either hot or cold ofa rapid circulation of the liquid heat transfer liquids. In one type ofsystem wherein mechanimedium from the primary heat exchange appacalmeans is employed for effecting forced circuratus through the flow lineto the branch supply lation,- the system is of such a character that,pipes forthe secondary heat exchange apparatus to all intents andpurposes, there is no circulawithout affecting the normal circulation ofthe tion when the circulating device is not in opermedium through theprimary heat exchange apation, that is, the system will not operate byparatus, or the secondary heat exchange appagravity alone. In anothertype of forced circuratus and the piping therefor, and without nelatingsystem, the circulating device is of such a cessitating the undueconsumption of power incharacter as to permit circulation of the liquid,cident to the mechanical circulating systems as by the passage of theliquid through a proheretofore known.

pelling member, when the mechanical-means is A still further object ofmy invention is the not in operation. When an auxiliary circulatingprovision, in a heat exchange system utilizing a device is installed inthe piping of a gravity operliquid heat transfer medium, of a method andated system, the friction resulting therefrom is apparatus whereby theabove mentioned objects such as to substantially impede thegravitational may be accomplished without in any way obflow. All suchauxiliary circulating devices funcstructing or interfering with thenormal opertion to circulate the liquid throughout the entire ation ofthe system in which my improvement system, including the heat exchangeapparatus is installed.

and the connecting piping, and substantially all In accordance with myinvention, the above the liquid in the system is circulated by thecirobjects are accomplished by moving a small yculating device when itis in operation. quantity of liquid through the ow line 4of the One ofthe objects'of the present invention is system, or a portion of the flowline, and through the provision, in a heat exchange system emanauxiliary circulating line preferably. arranged ployed for eitherheating or cooling purposes, of to connect the opposite ends of the flowline to an auxiliary circulating system whereby the flow thus provide aclosed circulating circuit, the

of the liquid heat transfer medium between the movement of liquidthrough the closed circulati primary heat exchange apparatus and thesecing circuit being maintained by means of a pump ondary heat exchangeapparatus may be accelor other suitable liquid circulating device.

erated without any substantial effect upon the The principle of myinvention, together with flow through the primary heat exchange appaasuitable arrangement of means for practicing the same, is illustrateddiagrammatically by the accompanying drawing wherein:

Fig. l illustrates the application of my improvement to an ordinaryunder-feed hot 'water heating system; and

Fig. 2 illustrates the application of my improveV ment to a down-feedcirculating system which may be utilized for circulating liquid in aheating system, a cooling system, or a system from which liquid, eitherhot or cold, may be withv drawn.

Except for the embodiment of myimprovement therein, the systemillustrated in Fig. 1 comprises a primary heat exchange apparatus suchas Y from the heat emitting appliances I 3. As is well understood, suchheat emitting appliances may connect to the flow pipe through branchreturns such as shown at I1. Such a system may be wholly gravityoperated, or suitable mechanical means may be employed therein, eitheralone or in conjunction with gravity, for producing a more rapidcirculation of the liquid heat transfer medium through the entiresystem, that is, through the heating device, the piping, and the heatemitting appliances, where a forced circulation is desired.

With a gravity operated system the flow of the liquid heat transfermedium from the heating device through the main flow pipe to the heatemitting appliances is comparatively slow, and, as a consequence, thereis a substantial drop in the temperature of the heat transfer mediumbetween the heating device and the branch supply pipes leading to theheat emitting appliances. Although it is not unusual to incorporate insuch a system some form of mechanical means for producing a forcedcirculation, such mechanical means is required to move the entire'volume of the liquid heat transfer medium in the system, that is,through the heating device, the flow pipe, the branch supply pipes, theheat emitting appliances and the return pipe, and the power necessary toeffect such a movement of the liquid is of considerable consequence.

In order to accelerate the flow of the heat transfer medium through theflow pipe 2V between the heating device i Il and the branch supply pipesI4 leading to the heat emitting appliances I3 and thereby minimize thetemperature drop in the heat transfer medium between the heating deviceand the heat emitting appliances, I provide a, closed circulatingcircuit comprising the main flow pipe, or a substantial portion thereofsuch as the horizontal portion I2, and a circulating pipe I8 preferablyconnecting the opposite ends of theilow pipe I2. It will be understood,however, that the delivery end of the circulating pipe I8 may connect toother points in the system such as the vertical ow pipe II, or the upperportion of the heating device Il. Circulation of the liquid heatingmedium through the closed circuit is induced by means of a pump or othersuitable circulating device I9 connected in the circulating pipe I8preferably near the junction of the terminus of the circulating pipe Ilwith lating device the ilow pipe I2. The circulating pipel I8 may be ofa size less than the size of the flow pipe I2.

Inasmuch as the capacity of thepump need only be such as to move aportion of the liquid heat transfer medium. through the circulatingcircuit, a minimum of power is required for the operation of myimprovement, and this' power is necessarily much less than the powerrequired Y for providing a forced circulation throughout the entiresystem. Furthermore, thecirculating device does not interfere with thenormal ow lof the heat transfer liquid, Ywhether such normal flow in thesystem be induced by gravity or by mechanical means or by both.

Where my improvement is embodied in a downieed liquid circulating systemsuch as that illustrated in Fig. 2 of the drawing. the liquid heattransfer medium may be delivered from the primary heat exchangeapparatus 2Il through the vertical portion 2| of the ow pipe in anysuitable manner, either gravitational or mechanical,\and the medium isthen conveyed through the horizontal portion 22 of the ilow pipe to thebranch supply pipes 23. The branch supply pipes may conduct the heattransfer medium to secondary heat exchange apparatus 24, whence it isreturned to the primary heatA exchange apparatus 20" through the returnpipe 25, or the liquid heat transfer medium may be delivered to thebranch supply pipe 26 for supplying a medium such as hot or cold waterto withdrawing devices 21. In case withdrawing devices are utilized insuch a system, it will be understood that suitable means should beprovided, such as supply pipes 32, for replenishing the liquid which iswithdrawn.

In order to accelerate the ow of the heat transfer medium in thehorizontal portion 22 of the flow pipe, the ends of this portion may beconnected through the circulating pipe 28 which, as indicated above, maybe of a smaller size than the horizontal flow pipe. Although it may beconnected otherwise as indicated above in the description of the systemillustrated in Fig. 1, the extreme end of the circulating pipe 28 ispreferably connected to thehorizontal flow pipe 22 at a point near thejunction of the vertical portion 2| therewith, and a pump or othercircu- 29 is connected in the circulating pipe 28 adjacent thisjunction.' If desired, a valve 30 or other suitable means may be placedin the circulating pipe 28 between the circulating device 29 and thejunction of the terminal of the circulating pipe with the `horizontalflow pipe 22 for controlling ilow of liquid in the closed circulatingcircuit. It may also be desirable to place a valve 3| in the circulatingpipe onv the opposite side of the circulating device in order that thecirculating circuit may be closed off entirely to permit the pump to berepaired or removed, or to discontinue the circulation of the liquid inthe auxiliary circuit.

As heretofore pointed out, the capacity oi the circulating device needbe sufficient only to move the liquid heat transfer medium through theclosed circulating circuit, and this circulation istion with ordinarytypes the opposite ends than the normal flow in the flow pipe whetherthe normal4 flow is induced by gravity or by mechanical means.

ratus and the secondary heat exchange apparatus the drop in thetemperature of the liquid between the primary and secondary exchangeapparatus is reduced, and this decreased drop in temperature is obtainedwith an expenditure of energy much less-than would be required to movethe entire quantity of liquid by the use of mechanical means forcirculating the liquid through the entire system.

My auxiliary circulating system, when incorporated in any ordinary heatexchange system in the manner herein described, operates to overcome thefriction head in the flow line of the old system and the total head inthe circulating line of the new system. The ultimate effect, therefore,is substantially that which would be obtained if the heating device orother primary heat exchange apparatus were movable into such positionswith respect tothe secondary heat exchange apparatus as to eliminate thehorizontal portion of the flow line from the system.

I have illustrated my improvement in connecof hot water heating systemsutilizing heating devices and heat emitting appliances such asradiators, and water withdrawing devices. It will be understood,however, that the improvement is equally applicable to cooling systemsand systems from which cold water or other liquid is withdrawn. Inasmuchas the operation of systems wherein a cold liquid is circulated does notdiffer essentially from the operation of the systems illustrateddiagrammatically herein, a further showing thereof is believed to beunnecessary. It will be understood, therefore, that the terms heatexchange system, primary heat exchange apparatus", secondary heatexchange apparatus and withdrawing devices are to be interpreted broadlyto include either heating systems, cooling systems, or systems forcirculating hot or cold liquids, so long as they operate in accordancewith the principle herein described.

Having thus described my invention, what I claim and desire to secure byLetters Patent is:

1. The method of circulating the liquid heat transfer mediumin a gravityoperated heat exy change system having a primary heat exchangeapparatus, a secondary heat exchange apparatus, means including ahorizontal flow pipe for conducting the medium from the primary heatexchange apparatus to the secondary heat exchange apparatus, and areturn pipe for conducting the medium from the secondary heat exchangeapparatus to the primary heat which consists in superimposing upon thegravitational head in a portion of the flow pipe a force suflicent tosubstantially accelerate the ow of the medium therein while maintaininggravitational flow through the return pipe.

2. In a heat exchange system, primary heat exchange apparatus, a flowpipe, including a horizontal portion for conveying a heat transfermedium therefrom, a return pipe for conveying the medium thereto,secondary heat exchange apparatus connected between the flow pipe andthe return pipe, a circulating pipe connected between of the saidhorizontal portion to provide therewith a closed circuit, and meansconnected in said circulating pipe for inducing flow of said medium insaid closed circuit to a`ccelerate the flow of said medium between thepri- As a result of this acceleratedy flow between the primary heatexchange appaexchange apparatus,r

mary heat exchange apparatus and the secondary heat exchange apparatus.

3. In a gravity heat exchange system, primary heat exchange apparatus,means, including a flow pipe, for conveying a liquid heat transfermedium therefrom, a circulating pipe connecting the opposite ends of theflow pipe to provide therewith a closed circulating circuit, returnpiping for conveying the heat transfer medium to the primary heatexchange apparatus, secondary heat exchange apparatus connected betweenthev iiow pipe and the return' piping, and means in the circulating pipefor circulating the heat transfer medium in the closed circuit toaccelerate the gravitational flow of the medium between the primary heatexchange apparatus and `the secondary heat exchange apparatus throughthe ow pipe.

4. In a heat exchange system, a primary heat exchange apparatus, asecondary heat exchange apparatus, a gravity operated circuit connectingsaid primary heat exchange apparatus and said secondary heat exchangeapparatus for conveying a liquid heat transfer medium from one heatexchange apparatus to the other, and means operating independently ofsaid primary heat exchange apparatus and said secondary heat exchangeapparatus to accelerate directly the flow of said medium in a portiononly of said circuit between said primary heat exchange apparatus andsaid secondary heat exchange apparatus.

5. In a heat exchange system having a heat supplying device, a heatemitting device, and means including a horizontal flow pipe forconveying a liquid heat transfer medium between said supplying deviceand said emitting device, means for acceleratingthe flow of the liquidheat transfer medium between said supplying device and said emittingdevice comprising a`closed circulating circuit including a portion ofsaid flow pipe and a by-pass for a portion of the liquid heat transfermedium around said heat supplying device, and means in said by-pass forinducing flow of the heat transfer medium in said circulatpipe and aby-pass around said heat supplying device, means in said by-pass forinducing flow of said transfer medium in said circulating circuit, andmeans in said closed circuit for controlling the flow therein.

'1. In a hot water heating system, a water heating device, a heatemitting appliance, means, including a flow pipe, for conveying theheated water between said heating device and said emitting appliance, areturn pipe for conveying the water from said emitting appliance to saidheating device, a circulating pipe connecting the end of said flow pipedistant from said heating device to the opposite end of said flow pipe,and means operating independently of said heating device to inducecirculation of the water in said system through said ow pipe and saidcirculating pipe.

8. In a gravity heating system, a heating device for heating a liquidheat transfer medium, a heat emitting appliance, means, including a flowpipe, for conveying the heat transfer medium from said device to saidappliance, a return pipe for conveying the heat transfer medium fromsaid appliance to said device, a circulating pipe connecting theopposite ends of said ilow pipe, and means in said circulating pipe forinducing circulation of said heat transfer medium through said iiow pipeand said circulating pipe.

9. In a hot water system, a water heating device, a iiow pipe, includinga horizontal portion, for transferring hot water from said heatingdevice to a water withdrawing device, a return pipe for returning waterfrom said withdrawing device to said heating device, a' closedcirculating circuit including said horizontal portion and a lay-passaround said heating device, and means in said by-pass for circulatingwater in said circulating circuit to accelerate the ow of water fromsaid heating device to said withdrawing device.

10. In a hot water system, a water heating device, a gravity operated owcircuit for transferring hot water from said heating device to a waterwithdrawing device and returning it to said heating device, said owcircuit including a horizontal portion through which the water iiowsfrom said heating device to said withdrawing device, a closedcirculating circuit including a by-pass around said heating device andsaid horizontal portion,4 and meansV in said by-pass, operatingindependently of gravity, i'or circulating water in said circulatingcircuit.

Y FREDERICK D. MENSING.

